pathPattern to match file extension does not work if a period exists elsewhere in the file name?

Question

I see numerous examples of using pathPattern to define an intent-filter for a specific file extension/type; for example, pathPattern=\".*\\\\.xyz\".

Unf

Answer 1

The android team chose an unfortunate way to implement pathPattern. You can take a look at how the pattern matching is implemented in the android.os.PatternMatch class:

https://github.com/android/platform_frameworks_base/blob/master/core/java/android/os/PatternMatcher.java

We're used to .* working like it does in a regular expression, where the * match is greedy and will match as many characters as possible. In PatterMatch's implementation, the match is not greedy. The .* will match as many characters as it can, until it finds a match for the next character in the string.

Example:

String: "/mnt/my.file.mytype"
pathPattern: ".*\\.mytype"

The ".*" in the pathPattern will match the substring "/mnt/my", and hence will fail to match the string.

Given this limitation, I don't see a way to write a pathPattern that can match any string that ends in ".mytype". The best you can do is follow Jason's solution to add additional patterns to match paths with as many dots as you are willing to specify patterns.